8. The Meaning of Quantum Mechanics

Engineers tend to be fairly matter-of-fact about the physics they use.
Many use entropy on a daily basis as a computational tool without
worrying much about its vague, abstract mathematical definition. Such
a practical approach is even more important for quantum mechanics.

Famous quantum mechanics pioneer Niels Bohr had this to say about it:

“For those who are not shocked when they first come across
quantum theory cannot possibly have understood it.” [Niels
Bohr, quoted in W. Heisenberg (1971) Physics and Beyond. Harper and Row.]

Feynman was a Caltech quantum physicist who received a Nobel Prize for
the creation of quantum electrodynamics with Schwinger and Tomonaga.
He also pioneered nanotechnology with his famous talk “There's
Plenty of Room at the Bottom.” About quantum mechanics, he
wrote:

“There was a time when the newspapers said that only twelve
men understood the theory of relativity. I do not believe there ever
was such a time. There might have been a time when only one man did,
because he was the only guy who caught on, before he wrote his
paper. But after people read the paper, a lot of people understood
the theory of relativity in some way or other, certainly more than
twelve. On the other hand, I think I can safely say that nobody
understands quantum mechanics.” [Richard P. Feynman (1965) The Character of Physical Law 129. BBC/Penguin.]

Still, saying that quantum mechanics is ununderstandable raises the
obvious question: “If we cannot understand it, does it at least
seem plausible?” That is the question to be addressed in this
chapter. When you read this chapter, you will see that the answer is
simple and clear. Quantum mechanics is the most implausible theory
ever formulated. Nobody would ever formulate a theory like quantum
mechanics in jest, because none would believe it. Physics ended up
with quantum mechanics not because it seemed the most logical
explanation, but because countless observations made it unavoidable.